A method for protecting a data entry device from eavesdropping includes masking a signature of entry resulting from entry of data by a user of the data entry device so as to reduce the detectability of the signature by eavesdropping. The signature may include a temperature differential in the data entry device from data entry by the user and the masking may include controlling the external temperature of the data entry device to reduce temperature differentials left in the data entry device by the user. Alternatively, the signature may include sound waves emitted from the data entry device and the masking may include masking sound waves emitted from the data entry device to reduce the detectability of the sound waves. A system may also be employed for protecting data entry to a data entry device from eavesdropping. The system includes a data entry device and means for masking a signature of entry resulting from entry of data by a user of the data entry device so as to reduce the detectability of the signature by eavesdropping.